1. Field of the Invention
This invention relates to hinge mechanisms for doors and particularly to such mechanisms which permit the door to be opened 180 degrees.
2. Description of the Prior Art
U.S. Pat. No. 521,772 discloses a mechanism employing a double pivot adjacent the jamb to allow a flush door to be opened 180.degree.. The double pivot involves a short link which connects recessed lugs on the frame with lugs on the door.
U.S. Pat. No. 2,177,826 shows an external compound action hinge construction which includes a link pivotally connected to the frame at one end and to the door at the other. There is a cam arrangement associated with the latter pivot connection which causes the latter connection to operate last when the door is closed and first when it is opened, to avoid interference between the inner corner of the door and the outer corner of the door frame during both opening and closing of the door.
In U.S. Pat. No. 2,870,477 a hinge arm pivotally connects the door and a truck body, the hinge arm extending through the door jamb. There is a cam detent mechanism between the hinge arm and the body and a second cam detent mechanism between the hinge arm and the door. When the door is moved from the closed position toward open the first mentioned detent mechanism yields first so that the door and hinge arm initially pivot as a unit with respect to the body. When the hinge arm reaches the end of its travel the second detent yields and the door then pivots with respect to the hinge arm to enable the door to reach the fully open position. When the door is closed the second detent yields first, causing the door to pivot first with respect to the hinge arm, after which the first detent yields and the door and hinge arm then move as a unit to the door closed position.
U.S. Pat. No. 3,085,297 discloses several embodiments of a complex door mechanism for a pressurized airplane cabin which is of interest with regard to the linkage which is used to achieve a 180.degree. door opening, particularly the first embodiment of FIGS. 1-11 and the second embodiment of FIGS. 12-18. These aircraft doors operate differently from the doors with which the present invention is concerned in that it is necessary first to "unplug" the door which has been hermetically sealed to the fuselage (by moving it inwardly), after which the door is then "sidled" out through the opening and finally is swung around about 180.degree. near the outer surface of the fuselage.
U.S. Pat. No. 3,651,539 shows a hinge construction wherein the hinge member on which the door is pivoted is held in a retracted position by a latch against the force of a compression spring while the door is closed. When the door starts to open the latch is disengaged; the hinge member moves outwardly perpendicularly to the plane of the door frame to move the door pivot axis out beyond the frame, and the door can then be opened 180.degree..
In all of the foregoing prior art constructions the hinge mechanism is recessed into the door jamb, works through the door jamb, or is otherwise closely associated with or adjacent the jamb. In the present invention such is not the case. Instead the hinge mechanism is mounted so that it is spaced away from the door jamb in confronting relation therewith.